In my experience, you will never notice a loss in image quality by going through a quality A/V receiver like the Denon you already own. While it is true there may be a bit of signal loss, it is so incredibly small, that you simply will not visibly see that loss.
What you lose is negligible considering you gain on screen menus as well as single point switching. As well, since the 3805 transcodes all incoming signals (game systems/vcr/etc.) to component video, you can truly leave your TV on the one component video input and let the receiver do every little bit of switching that you want it to do quite easily.
I always recommend going through the receiver when possible to simplify the setup.